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211.
Nina Sadlej-Sosnowska Lech Kozerski Elżbieta Bednarek Jerzy Sitkowski 《Journal of inclusion phenomena and macrocyclic chemistry》2000,37(1-4):383-394
Inclusion complexation processesinvolving four cyclodextrins and naproxen have beenstudied for the protonated and unprotonated forms ofthe guest molecule. The association constants havebeen evaluated from changes in the fluorescenceintensity of naproxen following addition of acyclodextrin to an aqueous naproxen solution. 1HNMR NOESY and ROESY spectra have shown that twoorientations of the guest molecule relative to-cyclodextrin are possible. 相似文献
212.
213.
A hierarchical classification of different concepts of shape of compact connected sets in R n (topological, Lipshitz, homotopic, Borsuk an homological shapes) is given. The most general among them is the homological shape. There is only a countable number of homological shapes for connected compact sets in R n . In the case n = 2 even the number of different Borsuk shapes for connected compact sets is countable. Giving a probability distribution of shapes we can define a shape entropy, a mean shape and shape fluctuations. This enables a formulation of information thermodynamics of shape and its applications to different fields (physics – small systems, chemistry, biophysics, pattern recognition). The paper does not develop yet these applications, its aim is to clear the basic notions. 相似文献
214.
215.
We consider dissipative systems resulting from the Gaussian and alpha-stable noise perturbations of measure-preserving maps on the d dimensional torus. We study the dissipation time scale and its physical implications as the noise level vanishes. We show that nonergodic maps give rise to an O(1/) dissipation time whereas ergodic toral automorphisms, including cat maps and their d-dimensional generalizations, have an O(ln(1/)) dissipation time with a constant related to the minimal, dimensionally averaged entropy among the automorphism's irreducible blocks. Our approach reduces the calculation of the dissipation time to a nonlinear, arithmetic optimization problem which is solved asymptotically by means of some fundamental theorems in theories of convexity, Diophantine approximation and arithmetic progression. We show that the same asymptotic can be reproduced by degenerate noises as well as mere coarse-graining. We also discuss the implication of the dissipation time in kinematic dynamo. 相似文献
216.
Koźmiński W Bednarek E Bocian W Sitkowski J Kozerski L 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,160(2):120-125
A new general J-HMQC-based technique is presented, which allows an accurate determination of heteronuclear coupling constants. The most important feature of this new approach includes acquisition of the two data sets with and without the additional pi(S)-pulse at the end of coupling evolution period. This enables preservation and separation of the two orthogonal terms of coupling evolution, which are manifested by in- and antiphase cross-peaks, respectively. The coupling magnitudes are evaluated by the nonlinear least-squares fitting of the ratios of integrated signal volumes for both kinds of signals. The effectiveness of the new sequence is demonstrated by determination of the 3J(H3'(i),P(i+1)) couplings in DNA octamer duplex d(GCGTACGC)(2) sample. Additionally, the ability of the new method for the measurement at the natural abundance level of 13C nuclei is presented for the beta-cyclodextrin. 相似文献
217.
Lech Stefaniak 《Magnetic resonance in chemistry : MRC》1978,11(8):385-389
Nitrogen chemical shifts constitute an effective means of distinguishing between isomeric benzazole ring systems. There is a large difference in nitrogen shielding, usually more than 20 ppm, between isomeric benzenoid- and quinonoid-like structures. 13C and 1H NMR is shown to provide unambiguous structure assignment only in cases of symmetric quinonoid ring systems of azoles. 相似文献
218.
The s-cis ? s-trans equilibrium of several enamino ketones and aldehydes, has been evaluated based on the results of aromatic solvent induced shift measurements and of protonation of the title compounds. In contrast to α,β-unsaturated ketones bearing no heteroatom, the Δδ3,cis value but not the Δδ3,trans, proved to be useful in conformational assignments. Protonation, which occurs mainly on oxygen, enhances the rotational barrier, thus enabling the observation of both rotamers at room temperature. Steric hindrance to conjugation enhances the rate of protonation at the carbon C2. 相似文献
219.
We consider some elementary proofs of local versions of CLARKSON 's inequalities and point out the fact that these inequalities can be generalized to hold for a much wider class of parameters. In particular it is easy to generalize our interpolation proof in various ways to higher dimensions. We point out explicitely some examples of such generalizations and we also prove some corresponding global versions. In this elementary way we obtain both new proofs of some previous results of this kind and also some new complements, unifications and further generalizations of these results. 相似文献
220.
The paper is concerned with order-topological characterizations of topological Riesz spaces, in particular spaces of measurable functions, not containing Riesz isomorphic or linearly homeomorphic copies of or .